Chronic ankle instability (CAI) is a common condition after lateral ankle sprain. CAI is characterized by mechanical and/or functional instability, or recurrent episodes of "giving way," persisting for at least 12 months after the initial injury, and is associated with limitations in activity and and participation. Contemporary theoretical models emphasize that CAI should not be explained solely by biomechanical or neuromuscular deficits, but rather as a dynamic condition shaped by the interaction of motor-behavioral, sensory-perceptual, psychological, and environmental factors.
Postural stabilization training is commonly used to improve balance and neuromuscular control in individuals with CAI. However, individuals with CAI may show increased reliance on visual information and altered visual-vestibular sensory reweighting during postural control tasks. The vestibulo-ocular reflex (VOR) contributes to gaze stability and visual clarity during head movements and may also be related to neurocognitive processes such as attention and processing speed. This study is designed as a randomized controlled, prospective, parallel-group, pretest-posttest design trial to investigate whether VOR exercises added to postural stabilization training improve visuo-motor reaction performance, fear avoidance behavior related to sports injuries and kinesiophobia in amateur athletes with CAI.
Being between 18 and 35 years of age.
Being classified as a Tier 2 athlete according to the McKay et al. Participant Classification Framework (trained/developmental level).
Having a history of at least one lateral ankle sprain (LAS) occurring at least 12 months before enrollment, resulting in swelling, pain, and functional impairment, and followed by persistent instability.
Having the most recent ankle sprain at least 3 months before study enrollment.
History of acute lateral ankle sprain within the last 3 months.
History of lower extremity surgery.
History of acute injury to other musculoskeletal structures of the lower extremity joints within the last 3 months that affected joint integrity and function and caused interruption of desired physical activity for at least one day.
History of balance or vestibular disorders, including cerebellar, vestibular, cochlear, or inner ear dysfunction.
Parallel
Postural Stabilization Training
Other interventionParticipants in this group will receive ankle joint mobilization followed by a structured postural stabilization training program. The program will include single-leg stance progression, hop stabilization tasks and number-sequence hop tasks. Exercises will be progressed according to the participant's ability to complete each task without errors. Ankle joint mobilization will include talocrural anteroposterior mobilization and distal fibular mobilization with movement, applied before the exercise session for approximately 5 minutes. The total session will last approximately 45 minutes and will be performed 3 times per week for 6 weeks.
Vestibulo-Ocular Reflex Exercise in addition to Postural Stabilization Training
Other interventionParticipants in this group will receive the same ankle joint mobilization and postural stabilization training program as the Postural Stabilization Training Group. In addition, vestibulo-ocular reflex (VOR) exercises involving fixation on a visual target during head movements will be implemented. VOR exercises will be structured to progressively increase postural demands and will include sitting, standing, walking, and single-leg stance positions. The total session will last approximately 45 minutes and will be performed 3 times per week for 6 weeks.
Reactive Balance Test
This test will be used to assess visuo-motor reaction performance during dynamic postural control. The test will combine the Y-Balance Test setup with a smartphone-controlled LED light system (BlazePod). LED targets will be placed at 80% of each participant's maximum reach distance in the anterior, posteromedial, and posterolateral directions. Participants will stand in the standard Y-Balance Test position and will be instructed to touch the target LED stimulus as quickly as possible without losing balance. A total of 45 randomized visual stimuli will be presented, with inter-stimulus intervals ranging from 0.5 to 2.5 seconds. Visuo-motor reaction time will be recorded in milliseconds, and accuracy will be calculated based on missed stimuli, multiple attempts, and decision errors. The test will be performed twice on the limb with a history of instability; the first trial will be used for familiarization, and the second trial will be used for analysis.
The Athlete Fear Avoidance Questionnaire - Turkish Version (AFAQ-TR)
The questionnaire will be used to assess fear-avoidance behavior related to return to sport after injury. The questionnaire consists of 10 items scored on a 5-point Likert scale ranging from 0 (strongly disagree) to 4 (strongly agree). The total score ranges from 0 to 40, with higher scores indicating greater fear-avoidance behavior.
The Tampa Scale for Kinesiophobia - Turkish Version (TSK-TR)
The scale will be used to assess fear of movement after musculoskeletal injury. The scale consists of 17 items scored on a 4-point Likert scale ranging from 1 (strongly disagree) to 4 (strongly agree). After reverse scoring items 4, 8, 12, and 16, a total score will be calculated. The total score ranges from 17 to 68, with higher scores indicating greater kinesiophobia.
Foot and Ankle Ability Measure Turkish Version (FAAM-T)
The Foot and Ankle Ability Measure Turkish Version (FAAM-T) will be used to evaluate postural stability and foot/anklerelated functional ability following chronic ankle instability and lateral ankle sprain. The FAAM consists of 29 items and includes two subscales: the Activities of Daily Living subscale (FAAM-ADL, 21 items) and the Sports subscale (FAAMS, 8 items). The Sports subscale is specifically designed to assess sport-related function and complex motor tasks and is widely used as a self-reported outcome measure in athletic populations. Scores are expressed as a percentage, with lower scores indicating greater sport-related functional limitation.
Cumberland Ankle Instability Tool - Turkish Version
The Cumberland Ankle Instability Tool is a 9-item questionnaire used to evaluate perceived ankle instability and functional limitations. The total score ranges from 0 to 30, with lower scores indicating greater ankle instability. A score of 24 or lower is considered consistent with functional ankle instability.
Weight-Bearing Lunge Test
The Weight-Bearing Lunge Test will be used to assess ankle dorsiflexion range of motion in a weight-bearing position. The maximum distance at which the knee can touch the wall without heel lift will be measured in centimeters. A dorsiflexion distance on the affected side that is ≥2.5 cm less than the unaffected side will be considered indicative of dorsiflexion limitation.
Dynamic Visual Acuity Test
The Dynamic Visual Acuity Test will be used to assess the functional status of the vestibulo-ocular reflex (VOR). Static visual acuity (SVA) and dynamic visual acuity (DVA) during active head movements will be measured, and the difference between these two values will be used as an indicator of VOR function. For both measurements, the smallest line that can be read with at least 50% accuracy will be recorded. The change in the SVA-DVA difference will be reported after the intervention.
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